The present invention relates generally to photosensitive materials and particularly to a novel group of polyphosphorus compounds comprising silver and chlorine which exhibit strong, permanent darkening on exposure to ultraviolet and short wavelength visible light.
The photosensitive of silver halides is well known and has long been utilized to provide photosensitive films of both emulsion and binder-free types. A background discussion of the prior art relating to silver halide emulsions and binder-free (e.g., evaporated) silver halide films for photographic applications is provided in U.S. Defensive Publication No. T966,003 to Maskasky.
It is also known that silver halide crystals can exhibit photosensitivity following encapsulation in a glassy matrix. U.S. Pat. No. 4,160,654 to Bartholomew et al. and U.S. Pat. No. 4,191,547 to Wu disclose photosensitive glasses incorporating silver halide crystals which visibly darken on exposure to ultraviolet light without any requirement for chemical or physical development.